Photosynthesis is a process by which green plants and some other organisms use sunlight to synthesize foods with the help of chlorophyll pigment present in the chloroplasts. During photosynthesis, the energy of sunlight is converted into chemical energy in the form of glucose and oxygen is released as a by-product. The overall process can be represented by the following equation:

6CO2 + 6H2O + sunlight ? C6H12O6 + 6O2

Here, carbon dioxide and water are taken in by the plant, and in the presence of sunlight, they are converted into glucose and oxygen. The process involves the conversion of light energy into chemical energy, which is stored in the form of glucose molecules. Hence, option 2, "Free energy is converted into potential energy and stored", is the correct answer.